Post on 03-Feb-2016
description
Palmer amaranth, benghal dayflower, and broadleaf signalgrass response to glufosinate applied alone or mixed
with 2,4-D, or dicamba
J.E. Chafin, A.S. Culpepper, and
L.B. Braxton
University of Georgia
Department of Crop and Soil Sciences
January 2010
Georgia counties confirmed to be infested with glyphosate-resistant Palmer amaranth.
2004 – 1 county
2005 – 2 counties
2006 – 7 counties
2007 – 10 counties
2008 – 18 counties
Glyphosate 3 lb
Pyrithiobac 0.25 lb
Biotypes with multiple resistance to glyphosate and ALS herbicides are becoming more common across Georgia.
0
20
40
60
80
100
Before (2004) After (2008)
88
26
% a
cres
25 2000
45
*Average of Macon, Taylor, Sumpter, Schley, and Dooly counties
Glufos. (Ignite)
systems
Cultivation Hand weeding
0
Impact of GR Palmer amaranth in Georgia counties with severe infestations.*
Acres (%) treated with at least two
residual herbicide
Dryland Conservation Tillage
Prowl + Reflex PRE
Roundup + Dual POST
Direx + MSMA PD
Prowl + Reflex PRE
Ignite + Dual POST
Direx + MSMA PD
Glufosinate 0.42 lb on 5 in. Palmer amaranth
“The challenge is making applications of glufosinate to target plants less than 10 cm in height” (Coetzer et al. 2002).
Future Technology: 2,4-D or Dicamba Resistant Cotton
2,4-D resistant cotton
2,4-D sensitive cotton
Objective
• Determine the response of glyphosate- resistant Palmer amaranth to glufosinate, 2,4-D (Weedar), or dicamba (Clarity) applied alone and glufosinate mixed with 2,4-D or dicamba.
• Carpetweed, benghal dayflower, broadleaf signalgrass, and pitted morningglory
Hypothesis
• Tank mixtures of glufosinate + 2,4-D or dicamba will be more effective in controlling broadleaf weeds than glufosinate alone.
Trial Locations
Macon County(Glyphosate-resistant Palmer amaranth)
Chula(Palmer amaranth, carpetweed)
Sunbelt Expo(benghal dayflower, broadleaf signalgrass, pitted morningglory)
Treatments
A factorial arrangement of two “glufosinate” options
and seven “tank mix” options
Ignite Option: None or Ignite at 0.42 lbs
Tank mix option: 2,4-D, dicamba, or none
– 2,4-D (Weedar 64) .5, 0.75, 1.0 lb/ac
– Dicamba (Clarity) .25, 0.5, 1.0 lb/ac– None
Application Methods
• Backpack sprayer
• Broadcast
• Overtop
• 15 gal/Ac
• Drift Guard T-Jet 11002 VS
• Early morning application
• 7-9 inch weed
Conditions at Time of Application
• Moist/Wet
• Sunny conditions
• Air Temperature: 76-95 F
• % Relative Humidity: 56-74
Data Reported & Statistical Analysis
• Palmer amaranth control was combined over the three locations.
• Carpetweed, benghal dayflower, broadleaf signalgrass, and pitted morningglory
• Weed control at 20 d is reported; interaction means are reported.
Percent GR Palmer amaranth control at 20 d. Average 3 loc., GA, 2009.
0
20
40
60
80
100
0.5 lb 0.75 lb 1.0 lb1.0 lb 0.25 lb 0.5 lb
2,4-D dicamba
69 cd
77 bc
73 bcd
79 b
65 d
77 bc
90 a
Glufos-inate
Herbicide applied alone
Non-treated glufosinate
12 DAT
2,4-D at 0.75 lb
12 DAT 24 DAT
dicamba 0.5 lb
12 DAT 24 DAT
0
20
40
60
80
100
69 cd
77 bc
Glufos-inate
0.5 lb
73 bcd
79 b
65 d
77 bc
90 a
0.75 lb 1.0 lb1.0 lb 0.25 lb 0.5 lb
2,4-D dicamba
91 a 92 a 96 a91 a 91 a
96 a
= control when mixed with Ignite
Percent GR Palmer amaranth control at 20 d. Average 3 loc., GA, 2009.
glufosinate glufosinate + 2,4-D 0.75 lb
12 DAT
glufosinate glufosinate + dicamba 0.5 lb
12 DAT
0
20
40
60
80
100
66 b 58
b
Glufos-inate
0.5 lb
99 a
63 b 55
b57 b
60 b
0.75 lb 1.0 lb1.0 lb 0.25 lb 0.5 lb
2,4-D dicamba
Percent carpetweed control at 20 d. Chula, GA, 2009.
2,4-D 0.5 lb at 10 DAT
0
20
40
60
80
100
Glufos-inate
0.5 lb 0.75 lb 1.0 lb1.0 lb 0.25 lb 0.5 lb
2,4-D dicamba
99 a 99 a 99 a 99 a 99 a 99 a
= control when mixed with Ignite
Percent carpetweed control at 20 d. Chula, GA, 2009.
66 b 58
b
63 b 55
b57 b
60 b
99 a
Benghal dayflower infesting Roundup Ready cotton
0
20
40
60
80
100
Glufos-inate
0.5 lb 0.75 lb 1.0 lb1.0 lb 0.25 lb 0.5 lb
2,4-D dicamba
Percent benghal dayflower control at 20 d. Sunbelt Expo, GA, 2009.
91 a
98 a
98 a
68 c
84 b
93 a
68 c
0
20
40
60
80
100
Glufos-inate
0.5 lb 0.75 lb 1.0 lb1.0 lb 0.25 lb 0.5 lb
2,4-D dicamba
97 a 94 a
= control when mixed with Ignite
Percent benghal dayflower control at 20 d. Sunbelt Expo, GA, 2009.
91 a
98 a
98 a
68 c
84 b
93 a
68 c
0
20
40
60
80
100
Glufos-inate
0.5 lb 0.75 lb 1.0 lb1.0 lb 0.25 lb 0.5 lb
2,4-D dicamba
Percent broadleaf signalgrass control at 20 d. Sunbelt Expo, GA, 2009.
96 a
0 b0 b0 b0 b0 b0 b
0
20
40
60
80
100
Glufos-inate
0.5 lb 0.75 lb 1.0 lb1.0 lb 0.25 lb 0.5 lb
2,4-D dicamba
93 ab
92 ab
= control when mixed with Ignite
Percent broadleaf signalgrass control at 20 d. Sunbelt Expo, GA, 2009.
91 ab
91 ab
88 b
92 ab
96 a
Pitted morningglory controlled 97 to 99% by all treatments
Everman et al. noted greater than 90% control with glufosinate applied POST on pitted morningglory.
Conclusions-Palmer amaranth
• Glufosinate alone only provided 73% control
• 2,4-D alone provided 69-79% control
• Dicamba alone provided 69-90%
• Tank mixtures of glufosinate+2,4-D or dicamba at least 91% control
• Glufosinate alone provided 99% control
• 2,4-D alone provided 58-66%
• Dicamba alone provided 55-60%
• All rates of glufosinate+2,4-D or dicamba provided 99% control
Conclusions-Carpetweed
Conclusions- Benghal dayflower
• Glufosinate alone provided 63% control
• 2,4-D provided 91-98% control; combinations with glufosinate could not improve control
• Dicamba control ranges from 68-93% but when combined with glufosinate control ranges from 93-97%
Conclusion-Broadleaf signalgrass
• Glufosinate alone provided 96% control and no control with 2,4-D or dicamba alone
• 2,4-D mixed with glufosinate, control ranged from 88-91%; at 1 lb/ac of 2,4-D the control was 8% less than glufosinate alone
• Dicamba mixed with glufosinate provided 92-93% control
Future Research
2,4-D resistant cotton
2,4-D sensitive cotton